Development of Tooth

Understanding the development of teeth involves untangling a complex process, especially focusing on deciduous teeth, which start developing in utero during the embryonic stage.

Timeline of Tooth Development

• 6 weeks of embryonic life:

  • The primitive oral cavity, or stomodeum, is lined with oral ectoderm (stratified squamous epithelium).
  • Connective tissue beneath is referred to as 'ectomesenchyme' and originates from Neural Crest Cells.
  • Basal cells of the oral ectoderm proliferate into the connective tissue, forming the Primary Epithelial Band.
  • This band is horse-shoe shaped, determining the position of future dental arches in the maxilla and mandible.

• 7 weeks of embryonic life:

  • The Primary Epithelial Band divides into:
    • Dental Lamina (inner, towards the tongue)
    • Vestibular Lamina (outer, forming vestibule)
  • Vestibular Lamina grows deep into connective tissue and undergoes degeneration to form the horse-shoe shaped sulcus, or vestibule.

Dental Lamina

• Horse shoe shaped plate crucial for tooth development.
• Shows increased cell multiplication in specific areas, forming Enamel Organ (localized thickening or placodes).
• Gives rise to all deciduous teeth and three permanent molars:
  • 1st molar: Initiated at 4 months fetal age
  • 2nd molar: 1 year after birth
  • 3rd molar: 5 years after birth
• Successional Lamina:
  • Develops from Dental Lamina in areas of deciduous teeth.
  • Gives rise to succedaneous teeth (permanent incisors, canines, and premolars).
  • Development from 5 months fetal age to 10 months after birth.

Degeneration and Remnants

• After 5 years, Dental Lamina degenerates as its function concludes.
• Epithelial cells replaced by connective tissue, severing connection with oral ectoderm.
• Remnants, called Cell rests of Serres, may remain, potentially leading to pathologies.

Enamel Organ and Tooth Germ

• Enamel Organ: Originates from placodes on Dental Lamina; gives rise to enamel.
• Dental Papilla: Beneath Enamel Organ; gives rise to dentin and pulp.
• Dental Sac/Follicle: Surrounds Enamel Organ and Dental Papilla; gives rise to cementum, periodontal ligament, alveolar bone.
• The collective of these structures is called the tooth germ.

Morphological Stages of Tooth Development

1. Bud Stage
2. Cap Stage
3. Bell Stage
   • Early Bell Stage
   • Advanced Bell Stage

Each stage reflects changes in the morphology of the Enamel Organ during development.